Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1575419 | Materials Science and Engineering: A | 2014 | 13 Pages |
Abstract
The present study concerns laser surface hardening (LSH) and melting (LSM) of AISI H13 tool steel using a high power continuous wave diode laser. Depth of surface hardened or melted layer increases with increase in incident laser energy density. Surface melting occurs at a higher laser energy density (>75Â J/mm2) and leads to the formation of inhomogeneous microstructure comprising non-uniform distribution of retained austenite, carbides (along inter-dendritic boundary) and martensite with their respective volume fractions varying with depth. Application of intermediate laser energy density (50-75Â J/mm2) yields a hardened layer with dispersion of ultrafine mixed carbides (M23C6, M7C3, MC or M2C). Laser treatment with a very low laser energy density (<50Â J/mm2) leads to formation of an over-tempered microstructure consisting of low carbon martensite and coarse carbide precipitates. Micro-tensile studies with specially machined samples from the surface melted zone following LSM with a laser energy density of 100Â J/mm2 records a high yield strength of 1310Â MPa along with poor ductility, marked by brittle failure. On the other hand, a similar sample from laser surface hardened zone treated with a laser energy density of 62.5Â J/mm2 yielded even higher yield strength of 1460Â MPa with a maximum elongation of 3.6%. Though both LSH and LSM produced higher yield strength compared to hardened and tempered AISI H13 tool steel, LSH yielded a combination of higher elongation (3.6%), than that after LSM (0.97%), with high yield strength and hence was considered a better option.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
G. Telasang, J. Dutta Majumdar, G. Padmanabham, I. Manna,